1. Field of the Invention
This invention relates to the field of methods for manufacturing a chemical compound having special utility as a soil fumigant and nematocide.
2. Prior Art
The use of 1,2-dibromo-3-chloropropane (hereinafter referred to as "DBCP") as a soil fumigant and nematocide is well known. For example, as discussed in U.S. Pat. No. 3,049,472, one method for ridding the soil of nematodes which attack plant roots is by applying DBCP to the soil in specific proportions. Other patents which teach the use of DBCP as a soil fumigant and nematocide are U.S. Pat. Nos. 2,849,361; 2,849,363; and 2,849,367. However, while the use of DBCP as a soil fumigant and nematocide is well known, recently the method in which it has been made has come under close scrutiny. It has come to light that DBCP may be the causal factor involved in the temporary sterilization of males involved in the manufacturing of such product. In the past, DBCP has been prepared by merely adding bromine to allyl chloride at low temperatures. One reason why low temperatures were used was because higher temperatures caused the reactants as well as the DBCP to vaporize. On the other hand if the reaction temperatures are too low, the reactants will react only to a limited degree. While mixing bromine with the allyl chloride at low temperatures will produce crude DBCP, it does not yield a complete conversion of all the allyl chloride. This is extremely desirable inasmuch as allyl chloride is chemically reactive and has a low flash point. Thus, too much allyl chloride in the DBCP could render it flammable. On the other hand, the use of excess bromine leads to the production of undesirable polybrominated products and also necessitates the post-reaction removal of the excess bromine.
Thus, while prior art processes do teach the production of DBCP, they require additional steps after the DBCP is initially made whereby the various impurities present are removed. The present invention relates to a process which overcomes the shortcomings of the prior art in that the DBCP can be made in a safe and efficient manner, but without the complex purification steps required by prior art processes.